The nomination, announced today by Defense Secretary Leon Panetta, includes a promotion to four-star general. If confirmed by the U.S. Senate, Kelly would oversee the nation's military activities in Central and South America and the Caribbean.

Kelly commanded Marine Forces Reserve and Marine Forces North for 16 months before he was tapped in March to become senior advisor to the secretary of defense.

Lt. Gen. Steven Hummer filled the New Orleans vacancy in August. The commands' headquarters are at the new Marine Corps Support Facility in Algiers, considered the anchor for the Federal City project.

Kelly is the highest-ranking U.S. officer to have lost a child to combat in either Iraq and Afghanistan. His son, 2nd Lt. Robert Kelly, a Marine infantry officer, was killed in Afghanistan on Nov. 9, 2010.

The U.S. Southern Command's headquarters is in Miami. It is one of the Defense Department's nine unified combatant commands. In addition to overseeing activities in places such as Guantanamo Bay, Cuba, Southern Command also oversees humanitarian missions in the region.